[FFmpeg-user] Decklink input buffer overrun

[Marton Balint]

On Wed, 23 Sep 2015, Ricardo Kleemann wrote:

> On Wed, Sep 23, 2015 at 12:47 PM, Flávio Pontes <flaviocpontes at gmail.com>
> wrote:
>
>> Hi,
>>
>> I need to stream the 2 inputs from a DeckLink Duo card in FHD.
>> So far I could compile ffmpeg with decklink support and capture one input
>> at a time without problems.
>>
>> When I try to capture from the 2 inputs I start getting the following
>> message repeatedly on both terminals:
>> [decklink @ 0x32287e0] Decklink input buffer overrun!
>>
>> I use these commands in the terminals:
>>
>> /opt/ffmpeg_build/bin/ffmpeg -f decklink -re -i 'DeckLink SDI (1)@7' -g 90
>> -s hd1080 -profile:v baseline -pix_fmt yuv420p -preset veryfast -c:v
>> libx264 -b:v 2000k -bufsize 1400k -minrate 2000k -maxrate 2000k -c:a
>> libfdk_aac -b:a 96k -threads 4 -f flv rtmp://10.12.20.62/myapp/tvines
>>
>> /opt/ffmpeg_build/bin/ffmpeg -f decklink -re -i 'DeckLink SDI (2)@7' -g 90
>> -s hd1080 -profile:v baseline -pix_fmt yuv420p -preset veryfast -c:v
>> libx264 -b:v 2000k -bufsize 1400k -minrate 2000k -maxrate 2000k -c:a
>> libfdk_aac -b:a 96k -threads 4 -f flv rtmp://10.12.20.62/myapp/tvescola
>>
>> I tried many combinations but couldn't get it to work.
>> I wonder if the input buffer is shared between the 2 inputs.
>> Is there any way to set an input buffer size independently for each
>> command?
>>
>> Thx in advance!
>> Flávio.
>> _______________________________________________
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>> ffmpeg-user at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/ffmpeg-user
>>
>
> Hi Flávio,
>
> I'm not sure if this directly addresses your problem, but have you tried
> using the -thread_queue_size parameter? I believe having a deeper queue
> might help, the default value is only 8. I've used much larger values, even
> 2048 for example.

Thread queue size only has an effect if multiple input sources are used. 
If a single input is used then reading from it is not threaded in the 
current ffmpeg.c implementation.

Regards,
Marton